U.S. Pat. No. 3,475,475 describes a process for the preparation of dialkyl zinc compounds by the following reaction: EQU Zn + R.sub.3 Al + RX .fwdarw. R.sub.2 Zn + R.sub.2 AlX
the patent teaches that the dialkyl zinc product of the reaction can be separated by distillation, preferably by vacuum distillation. For example, the patent teaches that diethylzinc, which has a boiling point of 27.degree.C at 10 millimeters Hg pressure, can be distilled from a mixture of diethylzinc and diethylaluminum chloride, as the latter has a boiling point of 91.degree.C at 10 millimeters Hg pressure.
Also, another known process for preparing dialkylzinc compounds involves the following reaction: EQU 2 R.sub.3 Al + ZnX.sub.2 .fwdarw. R.sub.2 Zn + 2 R.sub.2 AlX
the products are also separated by distilling the dialkylzinc compound from the reaction product mixture.
Yields of the dialkylzinc compounds are reported to be good, (around 80 percent or higher) and of high purity, however, the other reaction product, the dialkylaluminum halide is contaminated with soluble zinc. For example, during the preparation of diethylzinc a considerable amount of by-product di-n-butylzinc (bp 201.degree.C) is generated and remains in the still pot after the desired diethylzinc is distilled. The diethylaluminum chloride (bp 114.degree.C) co-distills with di-n-butylzinc, thereby making recovery of diethylaluminum chloride by distillation unsatisfactory.
Other conventional separation techniques, such as preferential complex-formation of one of the compounds are inapplicable.